Catalytic converter apparatus



Aug. 25, 1964 R. s. JOHNSON CATALYTIC CONVERTER APPARATUS 2 Sheets-Sheet1 Filed Aug. 12, 1960 INVENTOR. firvfi cZ/mson ATTORNEY Aug. 25, 1964 R.s. JOHNSON CATALYTIC CONVERTER APPARATUS 2 Sheets-Sheet 2 Filed Aug. 12,1960 AR \m ll|l|l llr llllllllllul'll u.

IN VEN TOR. 7%40/2 id 56125017 ATTORNEY United States Patent 3,146,073CATALYTIC CONVERTER APPARATUS Ralph S. Johnson, Rochester, Mich.,assignor to General Motors Corporation, Detroit, Mich., a corporation ofDelaware Filed Aug. 12, 1960, Ser. No. 49,256 3 Claims. (Cl. 23-288) Thepresent invention relates to a catalytic converter and more specificallyto the form and construction of the converter which enables the same tobe adapted to automotive applications.

Catalytic converters are generally well known devices in which theexhaust gases from an internal combustion engine are mixed with air andpassed through a chemical or catalyst bed where the unburnedhydrocarbons are oxidized or converted to substantially non-toxiccompounds prior to discharge into the atmosphere. In View of theincreasing smog problem that has developed in recent years, particularlyin large cities, there has been a resurgence of interest in thecatalytic converter as a means for substantially reducing the dischargeof unburned hydrocarbons into the atmosphere.

With the renewed interest in the catalytic converter, there has arisenthe problem of developing a converter which is commercially feasibleboth as to cost and its adaptation to an automobile. In adapting such aconverter to present day low profile automobiles, there is the problemof the relatively limited space available underneaththe car. The spaceproblem is particularly aggravated by the catalytic converter whichoperates at temperatures as high as 1,200 F.

Specifically, the present converter construction is of a very flatdesign withthe details of the invention being directed to the structuraland design features which make the fiat design feasible.

In particular, the present invention utilizes a uniquely canted orinclined catalyst bed which takes advantage of the variations inquantitative flow through the bed as the air proceeds longitudinally ofthe converter so as to permit the use of a small vertical displacementtype of converter.

Further structural innovations have been developed for strengthening orrigidifying the very fiat converter construction which would otherwisebe structurally too weak for practical utilization.

The details as well as other objects and advantages of the presentinvention will be apparent from a perusal of the detailed descriptionwhich follows.

In the drawings:

FIGURE 1 is a diagrammatic view of the converter;

FIGURE 2 is a partially sectioned plan view of the converter;

FIGURES 3,. 4 and are views, respectively, along lines 33, 4--4 and5--5- of FIG. 2;

FIGURES 6,. 7 and 8 are views. respectively, along lines 6 -6, 7--7 and8-8 of FIG. 5;v

FIG. 9 is a, view along line. 9-9 of FIG. 8;

FIG. 10 is a. view along line 10-10 of FIG. 2;

FIG. 11 is a view along line 1111 of FIG. 10.

The converter is indicated generally at 10 and includes a pair ofgenerally shallow dish-shaped casing members 121 and 1 4 whichv areadapted to be joined along oppositely facing flanges 16. and 18. Thecasings may actually be joined by any suitable welding process. bestseen in FIGS; 1 and 2, substantially identical ex haust gas and airinlet and outlet members are shown at 20 and. 22? and are suitablysecured to enlarged portions 24 and 26'. respectively of upper and lowercasing members 12 and 14.

Inlet member 20 includes a reduced cylindrical portion.

r 3,146,073 Patented Aug. 25, 1964 ice flaring portion 30 which extendssubstantially throughout the width of casing 12. Thus, the air andexhaust gas mixture which enters through portion 28 is introduced withinthe container substantially throughout its width whereby the gases areadapted to flow over the full width of the catalyst bed.

The catalyst bed container is indicated generally at 32. While theconstruction of the converter is readily adaptable to catalysts of manytypes and shapes, it has been particularly adapted for use with catalystparticles 34 which are cylindrical in shape and about of an inch indiameter and an average of A of an inch long. It will subsequently beseen that the construction of grid members 36 of catalyst bed 32 areparticularly designed to accommodate this type of catalyst particle.

The actual catalyst container is defined by the vertical side walls 38and 40 of casings 12 and 14 and the upper and lower grid members 36. Thegrid members are of identical construction and are secured to the casingmembers by identical means; therefore, the construction of only one ofthese members will be discussed in detail.

Before further referring specifically to the construction of theconverter, it is important to note that catalytic converter of the typebeing considered is subjected to a wide range of temperatures which overa very short period of time may vary from below freezing to atemperature in the catalyst bed of 1,200" F. It is immediately apparentthat with such a wide range of temperature variations, occurring over arelatively short period, the construction of the converter must takeinto account the inevitable expansion of materials which will occur whenutilizing a metal converter as contemplated.

Tobetter understand the structural significance of certain of thedetails which are about to be described, it would be helpful forillustrative purposes to indicate that a converter of the typecontemplated would be approximately 30 inches long, 10 inches wide andapproximately 3 /2 inches high. Thus, and this may best be seen byreferring" to FIGURES 2 through 5, the subject converter may be three tofour times as wide as it is high and three times as long as it is wide.This very flat converter construction would generally tend to bestructurally weak particularly if the converter casing materials aremade of the necessarily thin gauge metals utilized to keep down weightand: cost. It is contemplated that the casings and other converterelements would preferably be made of 20 gauge (.037 inch) type 302stainless steel.

The subject converter has been: constructed in a unique manner toachieve a very, thin or flat design with relatively light gauge metalsand which design nevertheless has the requisite strength to withstandanticipated wear.

Referring now to FIGS. 2 and 6-8, it will be seen that both of thecasing members 1 2 and 14 are longitudinally depressed. substantiallythroughout their lengths adjacent the casing center line to providelongitudinally and inwardly extending. strut members 42 and 441 By thusproviding the longitudinal struts on each of the casing members, it isapparent: that the converter longitudinal beam load capacity is greatlystrengthened.

A longitudinally extending support member 46 is provided to furtherstrengthen the converter construction and is adapted to" be secured tothe casing strut members 42'- and 44'. The configuration of supportmember 46 is shown in FIGS; 5 and 9 and includes a plurality oflongi'tudinally spaced tab portions 481 As best seen in FIGS. 2. and 8,walls 50 and 52 of each of the longitudinal struts 4 2 and 44' issuitably apertured along the casing center line to provide a. pluralityof slots 54 which correspond in shape and number to tabs 48' on supportmember 46. In assembling the converter, tabs 48 project through thecasing slots 54 after which the tabs are 3 welded in the area of theslots to secure support member 46 to the casings. In order to permittabs 48 to extend therethrough, grid members 36 are also suitablyslotted at 56, as shown in FIG. 9.

Holes 58 are provided in member 46 to reduce the weight of the memberand also to insure gas flow through the member. Canting or incliningcatalyst bed container 32 relative to the longitudinal axis of converteris a very important aspect of the present invention. By incliningcontainer 32 gas inlet chamber 60, defined by casing 12 and upper grid36, is of a progressively decreasing volume while outlet charnber 62,defined by lower grid 36 and casing 14, is of an increasing volume inrelation to gas flow from the inlet end to the outlet end of converter10. Inasmuch as gas flow through inlet and outlet gas chambers 60 and62, respectively, progressively decrease and increase from the inlet tothe outlet ends of the converter as the gases pass through the catalystbed, the inclined bed construction may be utilized. It is apparent thatinclining the catalyst bed reduces the overall height of the converterby taking advantage of the aforenoted inverse volume requirements of gasinlet and outlet chamber 60 and 62.

The tapered or inclined gas chambers or passages 60 and 62 also providea constant gas velocity throughout their lengths which results in bettergas distribution through the catalyst bed. To facilitate the canted orinclined construction of the catalyst bed container 32, as best seen inFIG. 1 longitudinal strut 42 of upper casing 12 tapers in depth from amaximum proximate the entrance of the converter to a minimum at theexhaust end of the converter. On the other hand, strut 44 of bottomcasing 14 tapers in the opposite sense proceeding from a minimumproximate the entrance of the converter to a maximum adjacent theexhaust end of the converter. The bottom walls 50 and 52 of thelongitudinal struts 42 and 44 are maintained in a parallel relationshipwith respect to each other even though they are inclined with respect tothe longitudinal axis of converter 10.

Referring particularly to FIGS. 2, 6 through 8, 10 and 11, theconstruction and mounting of the grid members 36 will now be consideredin greater detail. The grid material is generally the same type and sizeof stainless steel stock as that used in casings 12 and 14, supra. Asthe air and gas mixture enter inlet chamber 60 above the catalyst bed itmust, in moving longitudinally of the converter, flow through the bedand outlet chamber 62. Accordingly, grids 36 must be suitably slotted orperforated to permit the longitudinally flowing air to effectively passthrough the catalyst bed as illustrated by the arrows in FIG. 1. At thesame time, the grids must'be slotted or perforated in such a way as toretain the catalyst particles. These requirements have resulted in theunique grid construction shown in the aforenoted figures.

A plurality of longitudinally extending rows of de pressed portions 64are formed in grids 36 so as to provide a plurality of air openings 66extending transversely of the converter air flow. Depressed portions 64of grid 36 are formed by a punching process whereby these portions arepartially severed and depressed relative to the grid surface through theaction of a suitable punching member. In partially severing anddepressing grid portions 64, air openings 66 must be limited in size toprevent the catalyst particles from being lost therethrough.Accordingly, with the size particles suggested for illustrativepurposes, supra, the size of openings 66 is limited to approximately.020 inch. 1

In order to strengthen the depressed portions 64 of grid 36 and tothereby prevent distortion of openings 66, these portions are indented,as seen in FIG. 11, to provide a generally arcuate cross section asindicated at 67. By thus strengthening portions 64 it is insured thatthrough continued use the air openings 66 will not be come distortedfrom their original size.

As already noted, due to the extreme temperature variations to which theconverter is subjected, grids 36 are mounted upon casings 12 and 14 soas to provide a floating catalyst bed. In other words, grids 36 are notrigidly fixed to casings 12 and 14. Upper and lower casings Hand 14 arerespectively formed to provide flange portions 68 and 70. Angle brackets72, 74, 76 and 78 are suitably secured to the sidewalls of therespective casings adjacent flanges 68 and 70. As best seen in FIGS. 6and 7, grid members 36 are loosely supported between the flanges 68 and70 and adjacent angle brackets whereby the grids may move relative tothe casings and brackets to accommodate expansion and contraction of thegrid material due to the'aforenoted temperature variations. In thusloosely mounting the grid members undue stressing of the convertercasings are avoided. Tab slots 56 of grid members 36 are also madeoversize in relation to tabs 48 of support member 46 to permit gridexpansion without restraint by adjacent and supporting structures. Inorder to accommodate the intended canted or inclined disposition ofcatalyst bed 32, flanges 68 and 70 as well as angle brackets 72, 74, 76and 78 are likewise inclined in parallel relation to struts 42 and 44.

Inasmuch as there is a gradual attrition or wearing of the catalystparticles due at least in part to the mutually abrading relationship ofthe particles occasioned by vehicle induced vibrations, it is desirableto provide means whereby the catalyst bed may be automatically suppliedwith additional catalyst particles. To this end, a catalyst particlereservoir 80 is secured to upper casing 12 proximate the exhaust end ofthe converter. Reservoir 80 openly communicates through suitablyapertured casing 12 and upper grid 36 with catalyst bed 32. As thevolume of the bed tends to be diminished by the aforenoted particleattrition, additional particles within reservoir 80 will pass into thebed and restore or maintain the requisite bed particle volume. Due tothe canted or inclined construction of the catalyst bed and the locationof the reservoir near the highest end of the bed and further due to thenormal vibrations which occur, upon a diminution of the catalyst bedvolume, particles 34 would tend to move'toward the lower end of the bedpermitting the supplementary particles in reservoir 80 to move into thebed area. An opening 82 is'provided in reservoir 80 to permit therefilling of the reservoir with catalyst particles as the need developsover a period of extended converter use.

In order to insulate converter 10 from the vehicle body on which it ismounted, it is intended to wrap the main body of the converted with asuitable insulating material 84. For illustrative purposes, theconverter may be covered with an insulating material such as aluminumsilicate which is encased by a suitable aluminum wrapping 86. Inasmuchas the matter of insulation is more critical in the area of theconverter closest to the vehicle body, it is preferred that theinsulation be thicker on top of cover casing 12 than would be the casealong the lower casing 14.

Iclaim:

1. A catalytic converter having a gas inlet opening and a gas outletopening formed in spaced end walls thereof, said gas inlet opening beingdisposed to one side of a longitudinal plane passing through the centerof said casing and said gas outlet opening being disposed on the otherside of said plane, said converter comprising spaced first and secondelongated casing members respectively located on opposite sides of saidplane, a catalyst bed having perforated grid members located betweensaid casing members, a longitudinal strut formed on each of said casingmembers for stiffening the latter, each strut having a wall inclined tosaid longitudinal plane for maintaining said catalyst bed in an inclinedplane whereby said catalyst bed cooperates with said first and secondcasing members to define oppositely tapered inlet and outlet gas flowchambers respectively communicating with the gas inlet and outletopenings.

2. A catalytic converter having a gas inlet opening and a gas outletopening formed in spaced end walls thereof, said gas inlet opening beingdisposed to one side of a longitudinal plane passing through the centerof said casing and said gas outlet being disposed on the other side ofsaid plane, said converter comprising spaced first and second elongatedcasing members, a first strut member formed in said first casing member,said first strut member serving to stiffen said first casing member andbeing defined by a depressed portion that tapers from its deepest pointproximate the gas inlet end of the converter to its shallowest pointproximate the gas outlet end of the converter, a second strut memberformed in the second casing member, said second strut member serving tostiffen said second casing member and being defined by a depressedportion that tapers from its shallowest point proximate the gas inletend of the converter to its deepest point proximate the gas outlet endof the converter, an elongated catalyst bed, said catalyst bedcomprising a pair of spaced perforated grid members extending betweensaid first and second casing members, each of said strut membersextending from its associated casing member towards said catalyst bed soas to maintain the latter in a plane inclined to said longitudinal planewhereby said catalyst bed cooperates with said first and second easingmembers to define oppositely tapered inlet and outlet gas flow chambersrespectively communicating with the gas inlet and outlet openings.

3. A catalytic converter apparatus as set forth in claim 2 in which eachof said grid members is supported for expansion and contraction by oneof said casing members.

References Cited in the file of this patent UNITED STATES PATENTS1,794,276 Bowes Feb. 24, 1931 1,811,762 Schnell June 23, 1931 2,772,147Bowen et al. Nov. 27, 1956 2,776,875 Houdry Jan. 8, 1957 2,853,367 Karolet a1 Sept. 23, 1958 FOREIGN PATENTS 666,774 France May 28, 1929 142,388Australia Feb. 15, 1935

1. A CATALYTIC CONVERTER HAVING A GAS INLET OPENING AND A GAS OUTLETOPENING FORMED IN SPACED END WALLS THEREOF, SAID GAS INLET OPENING BEINGDISPOSED TO ONE SIDE OF A LONGITUDINAL PLANE PASSING THROUGH THE CENTEROF SAID CASING AND SAID GAS OUTLET OPENING BEING DISPOSED ON THE OTHERSIDE OF SAID PLANE, SAID CONVERTER COMPRISING SPACED FIRST AND SECONDELONGATED CASING MEMBERS RESPECTIVELY LOCATED ON OPPOSITE SIDES OF SAIDPLANE, A CATALYST BED HAVING PERFORATED GRID MEMBERS LOCATED BETWEENSAID CASING MEMBERS, A LONGITUDINAL STRUT FORMED ON EACH OF SAID CASINGMEMBERS FOR STIFFENING THE LATTER, EACH STRUT HAVING A WALL INCLINED TOSAID LONGITUDINAL PLANE FOR MAINTAINING SAID CATALYST BED IN AN INCLINEDPLANE WHEREBY SAID CATALYST BED COOPERATES WITH SAID FIRST AND SECONDCASING MEMBERS TO DEFINE OPPOSITELY TAPERED INLET AND OUTLET GAS FLOWCHAMBERS RESPECTIVELY COMMUNICATING WITH THE GAS INLET AND OUTLETOPENINGS.